RT Journal Article SR Electronic T1 Cost-effectiveness of vitamin D3 supplementation in older adults with vitamin D deficiency in Ireland JF BMJ Nutrition, Prevention & Health JO BMJ Nutrition FD BMJ Publishing Group Ltd SP 98 OP 105 DO 10.1136/bmjnph-2021-000382 VO 5 IS 1 A1 Laurence Francis Lacey A1 David J Armstrong A1 Emily Royle A1 Pamela Magee A1 L Kirsty Pourshahidi A1 Sumantra Ray A1 J J Strain A1 Emeir McSorley YR 2022 UL http://nutrition.bmj.com/content/5/1/98.abstract AB Background This study investigated the cost-effectiveness of vitamin D3 supplementation in older adults in Ireland, with year-round vitamin D deficiency (serum 25-hydroxyvitamin D concentration <30 nmol/L) (13% of Irish adults), from the perspective of the Health Service Executive.Methods Three age groups were investigated: (1) ≥50 years, (2) ≥60 years and (3) ≥70 years. Based on the clinical literature, vitamin D3 supplementation may: (1) decrease all-cause mortality by 7% and (2) reduce hip fractures by 16% and non-hip fractures by 20%. A discount rate of 4% was applied to life years and quality-adjusted life years (QALYs) gained, and healthcare costs. The annual healthcare costs per patient used in the model are based on the average annual health resource use over the 5-year time horizon of the model.Results The cost/QALY estimates in all three age groups are below the usually acceptable cost-effectiveness threshold of €20 000/QALY. The most cost-effective and least costly intervention was in adults ≥70 years. For this age group, the average annual costs and outcomes would be approximately €5.6 million, 1044 QALYs gained, with a cost/QALY of approximately €5400. The results are most sensitive to the mortality risk reduction following vitamin D3 supplementation.Conclusion The cost-effectiveness of vitamin D3 supplementation is most robust in adults ≥70 years. Clinical uncertainty in the magnitude of the benefits of vitamin D3 supplementation could be further addressed by means of: (1) performing a clinical research study or (2) conducting a pilot/regional study, prior to reaching a decision to invest in a nationwide programme.Data are available in a public, open access repository. All data relevant to the study are included in the article or uploaded as supplementary information. All relevant data are provided in the manuscript or the manuscript references; otherwise, 'not applicable'.